What is the Archangel and is there more than one?

The scriptures tell us that the foremost angel, both in power and authority, is the archangel (1 Thessalonians 4:16; Jude 9) and under the Archangel's authority would then be seraphs (Isaiah 6:1-3, 6, 7), cherubs (Psalm 80:1; 99:1; Ezekiel 10:1, 2), and angels (Genesis 19:1-26).

The prefix "arch," means "chief" or "principal," and implies that there is only ONE archangel, the chief angel; in the Scriptures. Further implying that there is only one archangel is that the word "archangel" is never found in the plural.

For much more, see:
Archangel